FXUS65 KBOI 300417
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
915 PM MST SUN NOV 29 2009

.DISCUSSION...INTENSE SURFACE HIGH CENTERED OVER IDAHO THIS EVENING 
WILL KEEP CLEAR AND COLD CONDITIONS IN PLACE OVERNIGHT.  IT APPEARS 
THAT THE AREA IS MORE PRONE TO FOG DEVELOPMENT TONIGHT WITH NEAR 
CALM WINDS...CLOSE TEMP DEWPOINT SPREADS IN SOME AREAS AND CLEAR 
SKIES.  THUS FAR HAVE NOT SEEN ANY FOG ON OBSERVATIONS BUT THINGS 
COULD CHANGE QUICKLY IN THE NEXT FEW HOURS. CURRENT FORECAST HAS 
PATCHY FOG ALONG THE SNAKE RIVER...AND THE NORMALLY FOGGY LONG 
VALLEY AND BAKER VALLEY IN OREGON. OTHERWISE...EXPECTING HIGH CLOUDS 
FROM THE NEXT UPSTREAM SHORT WAVE TO SPREAD SOUTHEAST DURING 
MONDAY.  LATEST FORECAST IS ON TRACK. NO UPDATES. 

&&

.AVIATION...VFR CONDITIONS EXPECTED THROUGH THE REMAINDER OF THE 
EVENING HOURS. SFC OBSERVATIONS INDICATING SEVERAL SITES GETTING 
NEARLY SATURATED THIS EVENING AND WITH THE LARGE SURFACE HIGH NEARLY 
OVER SOUTHERN IDAHO..WINDS ARE LIGHT WHICH MAY HELP WITH SOME LOCAL 
MVFR AND IFR CONDITIONS TO DEVELOP AFTER MIDNIGHT...ESP KMYL. 

&&

.PREV DISCUSSION...UPPER RIDGE WILL CONTINUE OVER OVER OUR CWA 
THROUGH MONDAY MORNING WITH LITTLE CHANGE IN TEMPS...WX...OR SKY 
COVER FROM TODAY/S CONDITIONS.  LATER MONDAY A SHORT WAVE TROUGH 
WILL COME IN FROM THE NORTHWEST AND FLATTEN THE RIDGE.  CURRENTLY 
THIS TROUGH IS MARKED BY A CLOUD BAND EXTENDING FROM BC SWWD INTO 
THE NORTH PACIFIC...BUT AS THE TROUGH MOVES INLAND THE CLOUDS WILL 
STRETCH AND THIN.  NO PCPN IS EXPECTED IN OUR CWA.  THE TROUGH WILL 
BRING COOLING TO HIGHER ELEVATIONS MAINLY IN IDAHO ZONES...AND 
SLIGHT AIR MASS MIXING AT LOWER ELEVATIONS FOR BETTER AIR QUALITY.  
OREGON ZONES WILL BE LARGELY BYPASSED BY THIS TROUGH.  TUESDAY WILL 
BE A COUPLE OF DEGREES COOLER THAN MONDAY AS UPPER FLOW TURNS FROM 
WESTERLY TO NORTHWESTERLY.

LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...LONG WAVE RIDGE WILL KEEP 
THE FORECAST AREA DRY WITH NEAR NORMAL TEMPERATURES FOR WEDNESDAY 
AND THURSDAY.  ONLY CONCERN WILL BE VALLEY TEMPERATURES.  DEPENDING 
ON HOW STRONG VALLEY INVERSIONS GET CURRENT MAX TEMPERATURE FORECAST 
MAY BE A FEW DEGREES TOO HIGH.  WILL NEED TO MONITOR INVERSIONS FOR 
THE NEXT FEW DAYS TO SEE HOW STRONG THEY GET THEN DECREASE MAX 
TEMPERATURES IF NEEDED.  BY FRIDAY MODELS CONTINUE TO HAVE PROBLEMS 
WITH THE TIMING AND PLACEMENT OF THE NEXT POTENTIAL WEATHER SYSTEM 
FOR THE REGION.  WITH SO MUCH UNCERTAINTY WITH THIS SYSTEM HAVE 
TRENDED POPS TOWARD CLIMATOLOGY FOR LATE FRIDAY AND THROUGH THE 
WEEKEND WITH TEMPERATURES NEAR NORMAL.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...GS
SHORT TERM...LC
LONG TERM....JA/LH
AVIATION.....CR